Hydraulic machine

ABSTRACT

A hydraulic machine comprising a substantially vertical main shaft, a runner secured to said shaft at the bottom end thereof, a casing arranged to enclose said runner, and an upper cover and a lower cover disposed in opposition to the upper and lower sides, respectively, of said runner. Said upper cover is formed to present a curvature from a part adjacent the main shaft to a part adjacent where the casing is mounted, such that said curvature becomes lower gradually, while said lower cover is formed to present a curvature from a part adjacent the draft tube to a part adjacent where the casing is mounted, such that said curvature becomes higher gradually.

United States Patent 1 Moriguti et a1.

[ HYDRAULIC MACHINE [75] Inventors: Kazuo Moriguti; Yukio Yamaguchi; Mutuo Suzuki, all of Hitachi, Japan [73] Assignee: Hitachi, Ltd., Japan [22] Filed: Aug. 17, 1973 [2]] Appl. No; 389,263

[30] Foreign Application Priority Data Aug. 21, 1972 Japan 47 82763 [52] U.S. Cl 415/161; 415/163 [51] Int. Cl. ..F01D 17/14 [58] Field of Search 415/219 C, 217,163,161, 415/129, 203, 205, 162, 164, 165, 166, 167

[4 1 Sept. 9, 1975 Primary Examiner-Henry F. Raduazo Attorney, Agent, or Firm-Craig & Antonelli [5 7] ABSTRACT A hydraulic machine comprising a substantially verti cal main shaft, a runner secured to said shaft at the bottom end thereof, a casing arranged to enclose said runner, and an upper cover and a lower cover disposed in opposition to the upper and lower sides, respectively, of said runner. Said upper cover is formed to present a curvature from a part adjacent the main shaft to a part adjacent where the casing is mounted, such that said curvature becomes lower gradually, while said lower cover is formed to present a curvature from a part adjacent the draft tube to a part adjacent where the casing is mounted, such that said curvature becomes higher gradually.

HYDRAULIC MACHINE BACKGROUND OF THE INVENTION This invention relates to a hydraulic machine such as hydraulic turbine r reversible pump-turbine and more particularly to the improved construction of the upper cover or the lower cover disposed in opposition to the upperside or the underside of the runner of such hydraulic machine.

Heretofore, the upper cover in this type of machinery has been constituted from a lower plate designed to directly receive water pressure, ribs adapted to reinforce said lower plate, and an upper plate, and the section along the runner axis presented mostly a box-like shape. This arrangement is to minimuze the cover deformation caused by water pressure in the cover and to prevent stick of driving shafts of guide vanes previded close to the outer periphery of the cover.

However, in this type of hydraulic machinery, fall or head is steadily raised up recently, with consequent enlargement in thickness of the lower plate, upper plate and ribs or in the distance between the upper and lower plates, that is, the height of the upper cover to such an extent where such cover takes an unneglectable weight proportion.

Increased height of the upper cover is necessarily attended by corresponding elongation of a stern of the guide vane, and usually, since about 20 or so pieces of guide vanes are provided along the entire periphery, they are also unneglectable in respect of weight, and hence it is desired to shorten the stem to the utmost.

Further, since the upper cover is assembled by welding, increased amount of welding is undesirable for the operation and also consideration must be given to the deformations caused by welding.

SUMMARY OF THE INVENTION The present invention has been deviced with the object of overcoming the above-said problems, and it is therefore an object of the present invention to provide a hydraulic machine provided with an upper or lower cover which is light in weight and small in size.

Another object of the present invention is to provide a hydraulic machine in which a portion of the upper cover and/or that of the lower cover, through which the stern operating the guide vane extends is thinned so as to allow use of a short stern.

An important feature of the present invention resides in the fact that at least the water pressure receiving portion of the upper cover provided in opposition to the upperside of the runner of the hydraulic machine is so shaped as to present a curvature which is lowered gradually toward the outer periphery of the runner. According to this arrangement, the water pressure received by the upper cover can be effectively dispersed on the upper cover surface, allowing use of a relatively thin material and further reduction of the cover thickness at the portion where the stem is mounted.

The above-described effect of the hydraulic machine according to the present invention will be further enhanced if the lower cover provided in opposition to the underside of the runner is formed with a curvature designed such that it will rise up gradually toward the outer periphery of the runner.

The further objects and advantages of the present invention will become apparent from considering the following detailed description of the invention and the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a partial sectional view of a hydraulic machine according to an embodiment of the present invention, showing a portion comprising a runner, an upper cover, a lower cover and a casing.

DESCRIPTION OF THE PREFERRED EMBODIMENT Now, an embodiment of the upper and lower cover assembly according to the present invention is described with reference to the drawing which shows, in section, a mechanism comprising a runner, an upper cover and a lower cover of a hydraulic turbine.

The main shaft 1 is disposed substantially vertically, and at the lower end of said shaft is secured a runner 2 which rotates with said shaft and is designed suited for high head. An upper cover 3 is provided in opposition to the upper face of said runner and a lower cover 4 in opposition to the lower face of said runner. A columnar fixture 31 is provided at a part adjacent the main shaft 1, that is, near the center of the upper cover 3, and a guide bearing 5 of said main shaft 1 is mounted at an upper part of said fixture 31 and a water sealing means 6 at a lower part of said fixture. Adjacent the outer periphery of the upper cover 3, that is, near its portion where a casing 9 is secured, there is provided a substantially box-shaped stem fixture 32 extending along the axis of said runner 2 and hollow in section. At an upper outer peripheral part of said fixture 32 is formed a substantially horizontally extending flange 33 designed to engage with said casing 9. That portion of the upper cover 3 which is positioned between a part adjacent the main shaft 1, preferably the upper face of the columnar fixture 31, and a part adjacent the casing 9, preferably the stern fixture 32, is shaped to present a curved face, preferably such as to form a part of a convex spherical surface, which becomes lower gradually from the portion adjacent the columnar fixture toward the stem fixture 32. On the inside of the spherical curved portion of the upper cover 3 are planted a plurality of ribs 34 which extend vertically and radially from the columnar fixture to reinforce said cover 3. In a space 37 in the interior of said upper cover 3 is also provided a baffle plate 35 which is fixed on said ribs 34 and suitably spaced apart from the runner 2 and is designed to prevent agitation of water. Said baffle plate 35 spans between the lower end of the columnar portion 31 and the stern fixture 32.

On the other hand, the lower cover 4 is formed with a curvature 43, preferably such as forming a part of a concave spherical surface, extending from a part adjacent the juncture 41 with the draft tube 10 to a part adjacent the casing fixed portion, preferably the stem fixture 42, with the upper face of said curvature being raised up gradually toward the stem fixture 42.

Between the underside of the stern fixture 32 of said upper cover 3 and the upperside of the stern fixture 42 of said lower cover 4 is defined a water passage extending from the casing 9 to the runner 2, and a guide vane 7 is disposed in said passage through a stem 8. Said stem 8 of said guide vane 7 is projected upwardly above the upper cover, and at the projected portion 81 thereof is provided a stem operating means 82 (the details thereof being not shown in the drawing).

The present invention has the above-described mechanism, so that the pressure water passed from the casing 9 through the guide vane 7 acts to rotate the runner 2 and then is flown out downstream. The pressure water filling the runner chamber is received by the upper and lower covers 3 and 4. Since each of said covers 3 and 4 is formed with a curved face as described above, the material composing the curved portions 36 and 43 may be smaller in thickness than that used in a boxlike sectioned structure, because pressure is dispersed both radially and tangentially. In case of forming a convex curvature as shown in the drawing, a large dead water portion 37 is produced between said curvature and the upper face of the runner 2 to increase loss of rotation of the runner 2, but such loss can be minimized by the baffle plate 35 provided with a suitable space from the upper face of the runner 2. (About 30 percent reduction of the material is possible for the cover).

If the spherical portions of the upper and lower covers 3 and 4 are arranged to terminate in the inside of the stem 8, the portion 81 of said stem 8 where the operating means 82 is provided can be formed closer to the guide vane 7 to allow shortening of the stem 8 as understood from the drawing.

If the upper and lower covers 3 and 4 are large in size, it is difficult to manufacture them in a unitary structure, so that, in such a case, it is advisable to divide the entire circumference into several segments and weld them together into an integral structure at the field. Also, when it is difficult to shape from a single sheet of steel plate or to practice integral casting, it is recommendable to weld together plural pieces of steel plates in the circumferential or radial direction to thereby form an integral assembly. Although in the shown embodiment the upper cover 3 is provided with a convex curvature, the same effect can be obtained by providing a concave curvature. Also, the lower cover 4 may be formed with a convex curvature.

When no ribs 34 are required, it needn't always provide them in either embodiment. The same holds true with the baffle plate 35. Also, the cover according to the present invention may not necessarily be of a perfect spherical shape, but may be formed by joining several segments of different radii.

What is claimed is:

l. A hydraulic machine comprising a main shaft disposed substantially vertically, a runner secured to the lower end of said shaft, a casing for introducing water into said runner, a guide vane provided between an end of said runner and the casing for controlling water supplied into said runner, a stem for operating said guide vane, an upper cover provided in opposition to the upperside of said runner, and a lower cover disposed in opposition to the underside of said runner, said upper cover comprising a columnar portion positioned near the center of the cover and having at its upper part a main shaft guiding bearing and at its lower part a water sealing means, a stem mounting portion positioned between the outer peripheral end of said runner and the casing and arranged such that the section along the runner axis will present a boxlike shape, a spherical portion positioned between the upper end of said columnar portion and said stem mounting portion, a plurality of spherical surface reinforcing ribs extending substantially vertically from the inside of said spherical portion and radially from said columnar portion and being formed integral with the inside of said spherical portion, and a baffle plate mounted on said reinforcing ribs between the lower end of said columnar portion and said stem mounting portion and disposed with a predetermined distance from the upper face of said runner.

2. A hydraulic machine according to claim 1, wherein said lower cover is provided with a curvature extending from a draft tube fixed portion to a casing fixed portion, said curvature being raised up gradually toward said casing fixed portion.

3. A hydraulic machine according to claim 2, wherein said curvature of said lower cover is part of a spherical face. 

1. A hydraulic machine comprising a main shaft disposed substantially vertically, a runner secured to the lower end of said shaft, a casing for introducing water into said runner, a guide vane provided between an end of said runner and the casing for controlling water supplied into said runner, a stem for operating said guide vane, an upper cover provided in opposition to the upperside of said runner, and a lower cover disposed in opposition to the underside of said runner, said upper cover comprising a columnar portion positioned near the center of the cover and having at its upper part a main shaft guiding bearing and at its lower part a water sealing means, a stem mounting portion positioned between the outer peripheral end of said runner and the casing and arranged such that the section along the runner axis will present a box-like shape, a spherical portion positioned between the upper end of said columnar portion and said stem mounting portion, a plurality of spherical surface reinforcing ribs extending substantially vertically from the inside of said spherical portion and radially from said columnar portion and being formed integral with the inside of said spherical portion, and a baffle plate mounted on said reinforcing ribs between the lower end of said columnar portion and said stem mounting portion and disposed with a predetermined distance from the upper face of said runner.
 2. A hydraulic machine according to claim 1, wherein said lower cover is provided with a curvature extending from a draft tube fixed portion to a casing fixed portion, said curvature being raised up gradually toward said casing fixed portion.
 3. A hydraulic macHine according to claim 2, wherein said curvature of said lower cover is part of a spherical face. 